• Proceedings of the KSME Conference
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• 2008.11a
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• pp.384-389
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• 2008

An accelerated fatigue test is essentially required to maintain the reliability of the actual structure of KTX under operation conditions. However, actual fatigue life cannot be obtained if specimens are not adequate to the conventional fatigue test. Moreover component maker did not provide data of loading stress (S) - cycles at the failure (N). In this study, we suggest a prediction method of the S-N curve for establishing an accelerating test under various load levels. Load history was acquired from the field tests. A Rainflow method was used on the cycle counting of the field load data, and then, an S-N curve was obtained through the iteration process under the condition that the damage index satisfies to 1 in the Miner's rule.

• Journal of the Korean Data and Information Science Society
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• v.27 no.3
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• pp.711-724
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• 2016

Under variable complex operating environment, various factors can affect the lifetimes of systems. In this research, we study bivariate reliability models having multiple dynamic competing risks. As competing risks, in addition to the natural failure, we consider the increased stress caused by the failure of one component, external shocks, and the level of stress of the working environment at the same time. Considering two reliability models which take into account all of these competing risks, we derive bivariate life distributions. Furthermore, we compare these two models and also compare the distributions of maximum and minimum statistics in the two models.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.751-757
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• 2012

An accelerated life test (ALT) is a test method that forces components to fail more quickly than they would under use conditions by applying higher overstresses. When two or more accelerating stresses are involved in an ALT, an interaction effect may occur. In previous studies, mostly ALTs without considering an interaction of accelerated stresses and accelerated life models were proposed. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at use conditions. We use the general log-linear relationship to model the dependence of life in the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use conditions and accelerated conditions by using mechanical component life data considering an interaction effect. Further, the accelerated life test method and acceleration factor model proposed in this paper will be the basis for adopting an accelerated life test with accelerated stress interactions.

• Journal of Korean Academy of Nursing
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• v.32 no.5
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• pp.599-608
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• 2002

Purpose: The purposes of this study were to test the validity and reliability of FACES III when applied to the only one and two family members, and to use more appropriately in the nursing practice. Method: Data were collected from 105 college students and 105 of their parents in two local nursing colleges. The original questionnaire, which was originally developed by Olson(1989), was modified by based on literature review and analyzed by correlation coefficient, Cronbach's α, Guttmans split coefficients and factor analysis. Result: Cronbach's αof the adaptability and cohesion were .77, .73(Guttmans split coefficient were .76, .71) when applied to the only one family member, and were .81, .77 (Guttmans split coefficient were .81, .77) when applied to two. The Pearson's correlation coefficient of the adaptability and cohesion between two family members were .38, .35. The total-item correlations of the other items except for items 5, 7, 13 were significant. The correlation coefficients between adaptability and cohesion when applied to only one and two were .30, .38(p < .01). When the data was analyzed by principle component analysis and Varimax rotation with the number of factors fixed to two, two factors explained 37.2% of total variance in the case of one member, and 42.2% of total variance in two. Conclusion: These results suggested that the concept and the construction validity of cohesion needed to be more clarified. Also It is required that the reliability and validity of FACES III should be tested in two more family members.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.2
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• pp.65-76
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• 2024

Purpose : This study aimed to develop and validate a reliable tool, the Korean physical therapists' work environment scale (K-PTWES), for assessing the work environment of Korean physical therapists. The study also sought to examine the validity and reliability of the instrument. Methods : This methodological study involved the development and testing of the measurement tool. The conceptual framework was established through a literature review and in-depth interviews with clinical physical therapists. A total of 40 meaningful statements emerged from this process, leading to the generation of 29 primary items. Following a content validity test, 29 items were selected for the preliminary tool. Data were collected from 220 physical therapists across various job roles and unit types, such as outpatient and inpatient physical therapy rooms in domestic hospitals, with more than one year of experience. The final analysis included data from all 220 physical therapists. Results : Varimax rotated principal component analysis was employed for validities, revealing four factors: organizational support, working system, sustainable development, and relationship with coworkers, explaining a total variance of 54.97 %. The Cronbach's α coefficient for the final tool was .939, indicating high reliability. Conclusion : In this study, we developed a measurement tool reflecting the characteristics of the Korean physical therapists' work environment scale (K-PTWES). Our findings highlight the tool demonstrated both validity and reliability. Utilizing this tool is expected to contribute to understanding the work environment of Korean physical therapists and fostering a healthy work environment. Based on our findings, we recommend, firstly, conducting research on the work environment and related factors of physical therapists working in diverse settings using the K-PTWES. Secondly, future studies should focus on validating the tool's criterion-related validity, as it was not addressed in this research.

• Journal of the Korea Safety Management & Science
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• v.18 no.1
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• pp.219-226
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• 2016

As the development environment is changing with the development of information communication technology, the systems that were used by each service became used with integration. In the process of integrating from existing legacy systems to new system, it should be smoothly integrated or shared, however, it cannot help holding existing technology or component due to significant cost burden for conversion. In this paper, it was not only classified by types with analyzing the various elements that make up legacy system but an approach and monitoring system were developed to each type. After System application results, data's information generated in each process is provided to other system in real time, so that it has not only secured the work efficiency and reliability but also it is made possible by integrating data in various formats for efficient data management, rapid search and tracking to history. With real-time monitoring system developed in this study, It can be very useful in a variety of industries which require real-time monitoring of distributed legacy system data.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2004.11a
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• pp.107-116
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• 2004

The advent of microarray technologies gives an opportunity to moni tor the expression of ten thousands of genes, simultaneously. Such microarray data can be deteriorated by experimental errors and image artifacts, which generate non-negligible outliers that are estimated by 15% of typical microarray data. Thus, it is an important issue to detect and correct the se faulty probes prior to high-level data analysis such as classification or clustering. In this paper, we propose a systematic procedure for the detection of faulty probes and its proper correction in Genechip array based on multivariate statistical approaches. Principal component analysis (PCA), one of the most widely used multivariate statistical approaches, has been applied to construct a statistical correlation model with 20 pairs of probes for each gene. And, the faulty probes are identified by inspecting the squared prediction error (SPE) of each probe from the PCA model. Then, the outlying probes are reconstructed by the iterative optimization approach minimizing SPE. We used the public data presented from the gene chip project of human fibroblast cell. Through the application study, the proposed approach showed good performance for probe correction without removing faulty probes, which may be desirable in the viewpoint of the maximum use of data information.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.3
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• pp.230-234
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• 2007

Generally, huge amounts of data traffic are generated by using broadcasting method to deliver sensing data to a sink node reliably so that it makes a severe network saturation problem resulting in unreliable data transfer. In order to handle this problem, a new congestion control protocol is required for supporting reliable data transfer, minimal use of energy and network resources at the same time in wireless sensor networks. In this paper, it proposes a Protocol to guarantee both a reliable transfer in data accuracy and minimum consumption of energy waste by using Hop-by-Hop sequence number and DSbACK(Delayed and Selective ACK Buffer Condition) scheme. In addition, it proves that reliability and energy efficiency are enhanced by the proposed method with the simulation results performed on TinyOS platform which is a component based built-in OS announced by UC Berkely with the performance comparison of other existing methods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.533-538
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• 2014

Power generator is one of the most important component of electricity generation system to convert mechanical energy to electrical energy. I t designed robustly to maintain high system reliability during operation time. But unexpected failure of the power generator could happen and it cause huge amount of economic and social loss. To keep it from unexpected failure, health prognostics should be carried out In this research, We developed a health prognostic method of stator windings in power generator with statistical data analysis and degradation modeling against water absorption. We divided whole 42 windings into two groups, absorption suspected group and normal group. We built a degradation model of absorption suspected winding using Fick's second law to predict upcoming absorption data. Through the analysis of data of normal group, we could figure out the distribution of data of normal windings. After that, we can properly predict absorption data of normal windings. With data prediction of two groups, we derived upcoming Directional Mahalanobis Distance (DMD) of absorption suspected winding and time vs DMD curve. Finally we drew the probability distribution of Remaining Useful Life of absorption suspected windings.

• Journal of Convergence for Information Technology
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• v.11 no.9
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• pp.138-144
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• 2021

In the electronic component assembly business, when product defects occur, it is important to track incoming raw material defects or work defects, and it is important to improve suppliers or work sites according to the results. The core task of the smart factory is to build an integrated data hub to process storage, management, and analysis in real time, and to manage cluster processes, energy, environment, and safety. In order to improve reliability through accurate analysis and collection of production data by real-time monitoring of production site management for electronic parts-related small and medium-sized enterprises (SMEs), the establishment of a smart factory is essential. This paper was developed to be utilized in the construction by defining the system configuration method, smart factory-related technology and application cases, considering the characteristics of SMEs related to electronic components that want to introduce a smart factory.